What does the PPS performance rating really mean?

[Vance Krier]

Hey Group,

How do you go about determining what the pps rating really means? I normally have just 'shotgun' designed small router configs based on the number and type of interfaces I needed, but I'd really like to know of a somewhat more scientific method to the madness.

For instance, I see that the new 2691 has a 70kpps throughput. What does this really mean? Is this based on 10byte packets, or 1500byte packets? How much stuff can I safely cram into that box?

Thanks,

Vance

[steve.barlow]

PPS is almost always based on 64 byte packet, as it increases the number (therefore looks better). If the packets were 1500 bytes, the number would be smaller due to serialization (delay to place a packet on the wire) and other factors. If the 2691 in your example is running at 70kpps, the cpu will be at around 90-100%. This is also fast switching, process switching will cut that number down greatly (I don't know the number for that router but I would guess down to no more than 15-20kpps).

Typically a 10Mbs port can put 14,800pps, a 100Mbs port 148,000pps and a gig port 1,480,000pps. That would be if the internal mechanisms (queuing, clocking in/out, processing, route-lookup etc) of the router/switch could handle that many pps.

Hope that helps.

Steve